eos-sleep-counter

#!/bin/bash

# After each second, show seconds remaining until this program exists.
#
# The output is displayed on one line.
# Pressing any key will stop this program.
#
# Exit code is
#   - 0 if any regular key was pressed
#   - 130 if the program was interrupted with Ctrl-C
#   - 142 if timeout occurred
#
# Parameters:
#   $1 = number of seconds (integer) before the program exists
#   $2 = (optional) prompt to show before showing the remaining seconds

printf2()  { printf "$@" >&2 ; }

ShowTime() {
    CountOfSubtrings() {
        # how many "substring"s there are in the given "string"
        local string="$1"
        local substring="$2"
        local length=${#string}
        local sublength=${#substring}
        
        string=${string//$substring/}
        local newlength=${#string}
        return $(( (length - newlength) / sublength ))
    }

    CountOfSubtrings "$prompt" "%s"
    case "$?" in
        1) printf2 "\r$prompt\r" "$s" ;;
        2) printf2 "\r$prompt\r" "$s" "$seconds" ;;
        *) printf2 "unsupported prompt '%s'\n" "$prompt" ;;
    esac
}

Main() {
    local -r seconds="$1"
    local prompt="$2"
    local s
    local ret=0
    local str=""

    [ -n "$prompt" ] || prompt="[Close in %s/%s seconds (or press a key to close)]"

    for ((s=seconds; s>0; s--)) ; do
        ShowTime
        read -t1 -n1 str
        ret=$?
        [ $ret -eq 0 ] && break
    done
    ShowTime
    if [ $ret -ne 0 ] || [ -n "$str" ] ; then
        printf2 "\n"
    fi
    return $ret
}

Main "$@"